Gas discharge lamps with sinuous discharge path between electrodes



Jan. 3, 1967 A. WALZ GAS DISCHARGE LAMPS WITH SINUOUS DISCHARGE PATHBETWEEN ELECTRODES 3 Sheets-Sheet 1 Filed Nov. 19, 1963 BY Alfred U 41 Wzzw/we 'T Jan. 3, 1967 WALZ GAS DISCHARGE LAMPS WITH SINUOUS DISCHARGEPATH BETWEEN ELECTRODES Filed NOV. 19, 1963 5 Sheets-Sheet 2 IN V ENTOR.

Jan. 3, 1967 GAS DISCHARGE LAMPS WITH SINUOUS DISCHARGE PATH BETWEENELECTRODES Filed Nov. 19, 1963 5 Sheets-Sheet 3 By ////re g/a/l UnitedStates Patent Claims priority, application Germany, Nov. 27, 1962,

W 33,421 4 Claims. (Cl. 313-404) The invention relates to a gasdischarge lamp with a discharge vessel composed of two preferablyaxially symmetrical parts open towards one side in the direction of theaxis of rotation, in which a helical discharge path following theaxially symmetrical parts is provided, at the ends of which path theelectrodes are arranged. Such a discharge vessel has a long dischargepath as compared with its dimensions, which has a favorable effect onthe degree of etficiency of the discharge lamp.

The object of the invention is to produce a discharge lamp with stilllonger discharge path and at the same time a particularly simpleconstruction, thereby making it easier to manufacture. The invention ischaracterized in that the discharge vessel is composed of twosubstantially smooth walled wall parts enclosing a hollow space ofannular cross-section in which a middle part with a helical depressionon each side is arranged, which is so constructed and dimensioned thatthe protrusions bordering the depressions contact the side surfaces ofthe wall parts enclosing the hollow space along a helical line, aclearance being however left free between the edge at the end of themiddle part having the largest diameter and the wall parts. The end ofthe middle part having the smallest diameter terminates in a tubularextension. The fluorescent layer is preferably applied on the middlepart so as to obstruct the egress of the light as little as possible. Inthis case the ignition strip is preferably covered by the layer offluorescent substance as otherwise a non-luminous strip would beproduced.

Several embodiments of the invention are hereinafter described withreference to the accompanying drawings, in which:

FIG. 1 is a sectional diagrammatic view of the first form ofconstruction, while FIGS. 2 and 3 are sectional diagrammatic views ofother preferred forms of construction.

In FIG. 1, and 11 designate two axially symmetrical parts forming theouter boundary of the discharge vessel, the generatrix of which parts issubstantially a straight line or a curve. In the end of the vesselhaving the smallest diameter, a socket 12 is inserted which has atubular extension 13 in which one of the electrodes 14 is arranged. Inthe annular space between the wall parts 10 and 11 there is a middlepart 15 provided with helical depressions dividing the discharge vesselinto spaces 16 to 26. The middle part 15 is so constructed that theprotrusions formed by the depressions contact the side surfaces of thewall parts 10 and 11 along a helical line so that the individual spaces16 to 26 are sealed off from each other with the result that a helicaldischarge path is formed which extends from the electrode 14 to theelectrode 27. The middle part 15 is so dimensioned that its edge 1512 atthe end having the largest diameter does not touch the wall parts 10 and11 so that here the discharge path can pass over from the inner side tothe outer side of the middle part 15. When the discharge vessel isconstructed in this manner it is possible to arrange both electrodes 14and 27 of the lamp at the end carrying the socket 12, with the resultthat the construction of the lamp is simplified considerably becauseotherwise the lead to the electrode arranged at the other end of thelamp would have to run through the discharge space. This,

3,296,480 Patented Jan. 3, 1967 however, would present greatdifiiculties because the lead must be well insulated and only insulatingmaterial can be used which contains no imprisoned gases and does notdecompose when subjected to ultraviolet radiation.

The middle part 15, when constructed according to the invention, is acomponent part of both sections 16 to 21 and 22 to 26 and, through beingcoated with fluorescent substance on both sides, is utilized twice. As aresult, as compared with the conventional fluorescent tubes which areonly internally coated with fluorescent substance, that is only on oneside, the length and volume of the discharge path are greater with agiven quantity of glass. Therefore the gas discharge lamp according tothe invention has a great light intensity while being of smallerdimensions. The middle part 15 terminates at its end with smallestdiameter in a tubular extension 15a which can be slipped on to thetubular extension 13 of the socket 112 with slight play. Thus adischarge path is produced which extends for example from the elect-rode14 to the electrode 27 via the spaces 16 to 26. The electrode 27 ispreferably connected to the socket 12 through the intermediary of asteadying resistance. This steadying resistance can be arranged insidethe discharge vessel. In the example illustrated, it consists of anincandescent lamp 28.

The wall parts 10 and 11 can be made in a very simple manner in a singleoperation by blowing, as indicated by the dash lines in the drawing. Thebody produced is then parted along the line 29. The middle part 15 ismade separately and placed in the part It the tubular extension 15abeing slipped on to the tubular extension 13 of the socket. Thefluorescent substance is preferably applied on the part 15. It serves atthe same time for improving the seal between the protrusions of themiddle part 15 and the wall parts 10 and 11 and between the tubularextensions 13 and 15a. To obtain a perfect seal between the parts 15 and10, 11 as well as 13 and 15a, it is possible to use instead of or inaddition to the fluorescent substance, a substance which is particularlystable in a vacuum and chemically resistant to UV. radiation. The part15 may also carry an ignition strip which facilitates the lighting ofthe gas discharge lamp. The ignition strip is preferably applied beforethe fluorescent substance so that it does not cause any dark places onthe middle part 15.

After the middle part 15 has been fitted, the part 11 shown in dashlines is inverted and also placed in the part 10. Thereupon the two wallparts 10 and 11 are welded together at the join 30 in known manner, orthey can be cemented together with a suitable material such as Araldit.

The space exclosed by the wall parts 10 and 11 is then exhausted in theusual way and subsequently provided with a gas filling and a mercuryadditive.

As already mentioned, the fluorescent substance is preferably appliedonly on the middle part 15 and in a layer thickness yielding the maximumquantity of light which can be considerably greater than in the case ofthe standard lamps in which, as is known, the layer of fluorescentsubstance obstructs more or less considerably the passing out of thelight. The two wall parts 10 and 11 are preferably free from fluorescentsubstance. They may, however, also be provided with a coat offluorescent substance, in which case, however, this coat is kept verythin so as to obstruct the egress of light as little as possible.

FIG. 2 shows a modified form of construction in which spherically domedwall parts 40 and 41 are used which are better able to withstandexternal air pressure. 42 is the middle part, the helical depressions ofwhich in combination with the wall parts 40 and 41 form spaces 43 to 51.The wall part 41 is first blown in one piece with the wall part 40 asshown in dash lines, and then parted along the line 56, turned upsidedown and welded to the wall part 40 in the manner described inconnection with the first embodiment illustrated in FIG. 1. 52 and 53are the electrodes. The tubular extension 42a of the middle part 42 isslipped on to the insertion 54. 55 is the screw socket.

The embodiment illustrated in FIG. 3 differs from that of FIG. 2 in thatan intermediate or middle part 60 which is constructed as a rotary part,has on both sides substantially helical or spiral webs 60a and 60bwhich, when the lamp is assembled, bear against the smooth wall parts40, 41 and thus produce the helical discharge passage 61 to 72.

The middle part 15 can "be made of electric conducting materials, e.g.of iron sheet, coated with a layer of glass or enamel insulating theconducting material from the discharge spaces. A middle pa-rt of such aconstruction is easy to produce and serves in an ideal manner as anignition strip which facilitates the lighting of the gas discharge lamp.

What I claim is:

1. A gas discharge lamp comprising, in combination, two smooth-surfacedwall parts which are coaxial surfaces of revolution and define betweenthem a sealed annular space whose diameter is substantially less at oneaxial end than at the other axial end; a middle part disposed within andalong said annular space and having helical projections on both itsradially inner surface and its rdially outer surface, each helicalprojection being in sealing contiguous relation with the smooth innersurface of the respective adjacent wall part; each projection forming,with the Wall part in contact therewith, one part of a discharge path,and corresponding axial ends of the two parts of the discharge pathcommunicating with each other at the larger diameter end of said annularspace; and a pair of electrodes each positioned at the other axial'endof a respective part of the discharge path.

References Cited by the Examiner UNITED STATES PATENTS Nisbet 313*20'41,602,245 10/ 1926 7 2,316,348 4/1943 Mahlet 313220 2,938,137 5/1960Roger et al. 313- 197 2,985,787 5/1961 Scott 13-220 FOREIGN PATENTS853,616 10/ 1952 Germany.

906,245 3/ 1954 Germany.

697,087 9/ 1953 Great Britain.

JAMES W. LAWRENCE, Primary Examiner. C. R. CAMPBELL, Assistant Examiner.

1. A GAS DISCHARGE LAMP COMPRISING, IN COMBINATION, TWO SMOOTH-SURFACEDWALL PARTS WHICH ARE COAXIAL SURFACES OF REVOLUTION AND DEFINE BETWEENTHEM A SEALED ANNULAR SPACE WHOSE DIAMETER IS SUBSTANTIALLY LESS AT ONEAXIAL END THAN AT THE OTHER AXIAL END; A MIDDLE PART DISPOSED WITHIN ANDALONG SAID ANNULAR SPACE AND HAVING HELICAL PROJECTIONS ON BOTH ITSRADIALLY INNER SURFACE AND ITS RADIALLY OUTER SURFACE, EACH HELICALPROJECTION BEING IN SEALING CONTIGUOUS RELATION WITH THE SMOOTH INNERSURFACE OF THE RESPECTIVE ADJACENT WALL PART; EACH PROJECTION FORMING,WITH THE WALL PART IN CONTACT THEREWITH, ONE PART OF A DISCHARGE PATH,AND CORRESPONDING AXIAL ENDS OF THE TWO PARTS OF THE DISCHARGE PATHCOMMUNICATING WITH EACH OTHER AT THE LARGER